Few people bother to read an entire privacy policy or terms of service for every service they use. Even less bother with the changes services make to those terms over time. Docracy Terms of Service Tracker is a webapp that tracks when words change so you can keep up to date without reading the whole thing.

Docracy uses a document change analysis to track when terms of service and privacy policies are updated, so anytime a site changes their terms, Docracy knows. In most cases, it's just a couple edits to change the language, but sometimes they're a lot more comprehensive. Terms of Service change all the time, and while companies usually notify you of the changes, you probably don't actually bother reading through them. This is an easy way to track what has changed so you can see if it matters to you. Of course, you'll need to have at least skimmed the Terms of Service to begin with.